I Built a Privacy-First, Syntax-Aware Diff Tool because 'Text Compare' Wasn't Enough

Source: Dev.to

The problem with generic diff tools

We’ve all been there: you have a local version of a file and a version from production (or a snippet from StackOverflow), and something is breaking. You paste them into a generic “Online Diff Checker.”
The result? A wall of black text with red and green backgrounds.

While this works for plain English, it is terrible for code. Without syntax highlighting, skimming through 500 lines of JSON, Rust, or Python to find a missing bracket or a variable‑type change is mentally draining.

Most online tools also require you to upload your data to their server to process the diff. If you are working on proprietary code, API keys, or client data, pasting that into a random web form is a security nightmare.

Diff Guru: privacy‑first, syntax‑aware diff

Diff Guru solves the privacy issue by running 100 % client‑side with unlimited merge capabilities. The latest update adds language‑specific syntax highlighting, so you get the same coloring you’re used to in VS Code.

Supported languages and formats

• Modern stack: TypeScript, JavaScript, React/JSX
• Backend: Python, Go, Rust, Java, C#, PHP, Ruby
• Systems: C, C++, Dockerfile
• Mobile: Swift, Kotlin
• Data / config: JSON, XML, YAML, SQL, CSS, SCSS

Seeing keys in one color and string values in another makes JSON structures pop instantly. Highlighting lifetimes and macros in Rust helps you separate logic changes from syntax noise.

Try it out

You can try the specific tools based on your stack:

• 🐍 Python Diff Checker
• Rust Diff Checker
• Java Diff Checker
• Dockerfile Diff

Roadmap

I am currently working on adding even more languages.

Feedback

I built this tool to be free, fast, and private. If you find a missing language or a bug in the highlighting, let me know in the comments.

Happy coding!